Porcelain balls are utilized to achieve bright finishes without the use of steel media. Because of its shape, it imparts a single point of contact resulting in a very fine finish to almost any area it can REACH. Porcelain balls will not leave impingement marks that steel media produces on some other softer metals and/or flat surfaces. Their lighter weight lessens the distortion potential for lighter work and wire forms. Very popular for delicate parts, fine edge blanking and precious metal burnishing. Use with Raytech compound D. Mixing the sizes is recommended for good Vibratory action. Please note that a break-in period of 4 to 6 hours is required. Density: 125 lbs/cu ft.